There has been extensive research directed to the preparation and evaluation of aryl phosphites as polymer stabilizers. While some of these have been made available commercially many of them have limited application because of deficiencies that limit their general application. Typical of these deficiencies are lack of hydrolytic stability, both on the shelf and in use, and in a particular application, undesirable potential water carry over in polypropylene processing. Improved aryl phosphites that provide heat and oxygen resistant antioxidant compositions when combined with hydroxyphenylalkyleneyl isocyanurates are desired that also are resistant to hydrolysis.